Safety locking device for manhole covers



May 18, 1926. 1,585,372

C. L. BURNHAM SAFETY LOCKING DEVICE FOR'MANHOLE COVERS Filed June '2, 1922 E I W Burn/1a Fatented l -flay l8,

CLIFFORD I1, BUBNHAM, QF CHICAGO, ILLINOIS.

SAFETY LOCKING- DEVICE FOR MANHOLE COVERS.

Application filed June 53,

This invention relates to mechanism to prevent the removal of a tank manhole cover while any dangerous pressure exists within the tank. This device has particular reference to tanks intended to contain volatile fluids under atmospheric pressure w iich may from the nature of the fluid generate pressure within the tank due to external heat or agitation, etc. F or example, a tank car containing gasoline may )8 heated to such an extent by the direct rays ot the sun that a dangerous pressure is built up within the tank, and an attempt under such conditions to remove the manhole or dome cover for unloading would suodenly release this pressure with disastrous results.

It is an important object of this invention to provide a safety locking mechanism for container closures that is automatically locked by an increasein pressure in the tank and unlocked by releasing the pressure in the tank.

It is a further object of this invention not only to prevent actual removal 01" the cover under the conditions specified but to prevent unscrewing the cover suiliciently to release the tank pressure through the gasket under the cover.

Qther and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a top plan view of a cover, embodying the device of my invention.

Figure 2 is a slightly enlarged sectional elevation on the line 22 of Figure l.

Figure 3 is a bottom plan view of the cover drawn to the same scale as Figure 2.

As shown on the drawings:

The reference numeral 1 refers to a tank or container having an opening 2 surrounded by a collar 3 riveted to the tank- It is to be understood that a suitable collar can be attached to the dome commonly used with tank cars, and that the collar can be formed for attacl ment to the rounded top of a cylindrical or spherical tank. The collar 3 has equally spaced downwardly pro jecting lugs l adapted to be engaged by the locking mechanism to be described hereinafter. A cover member 5 is threaded to en- 1922. Serial No. $35,376.

t gasket joint thereof. As show collar is apertured For a diaphra member T engaged thereto by tl'ireads. A diaphragm 8 securely held against a shoulder of the member 7 y the annular ex nally threaded lock nuts 9. The diaphi .gm 8 is protected by a housing 10, preferably an integral part of the cover 5, provided with air vents 11. i

A rod 12 is secured at the center of the diaphragm Sand leads to a yoke 13 to which are pivoted links 14 pivoted at their other ends to locking bars 15. The cover is provided with equally spaced (lownwardly extending lugs 1G similar to the lugs 4; except that they are apertured for the locking bars 15. The collar 3 is provided with any suitable marking means such as the projections '17 intended to show the location of the lugs a when the. cover 5 is in position. The cover also has one marking projection 18 to indi cate the position of one of the lugs 16 thereon.

mating The operation of my device is dependent phragm 8 due to an increase in 3ressure within the tank. The degree of pressure required to buckle the. diaphram is of course dependent on the material and gauge of the plate forming it; and any desired op erating pressure differential is easily obtained by using a properly constructed dia phragm. The nulge in the diaphragm lifts the rod 12 and the yoke 13 at-t ched thereto. thus straightening out the toggles formed by links 1'1, and so moving the bars 15 outwardly into a position beneath the edges of the collar 8 which would prevent removal of the cover. The lugs l on the collar prevent rotation of the cover when the bars 15 are extended as the bars would strike the lugs. The marking means on the outside of the collar and cover is provided to insure the cover bei g; screwed into a position Where the lugs 16 will not match the lugs t and thus prevent projection of the bars It will be evident that as the bars 15 re equally spaced around the cover th' togole My safety locking mechanism is equally suitablet'or other forms of sealed openings Wher in a pressure might be developed Within the container that would render removal of the closure a matter of danger to-the Workmanv The marking means 1'? and 18 are provided to enable the workman who puts on the cover to screw it into a position where the lugs 4iand 16 are not in line to prevent the locking bars from striking the lugs at I am aware that numerous details of construction may be varied through a Wide range Without departing from the principles of this invention, and I therefore do not purpose limiting: the patent granted otherwise than necessitated by the prior art.

I claim as my invention:

1. A tank closure comprising a collar having a plurality of equally spaced downwardly projecting lugs adjacent the bottom of the openii'ig therethrough a cover adapted to be secured to said collar having" an equal number of downwardly projecting lugs thereon corresponding in position with the lugs on said collar, a diaphragm in said cover, an operating rod attached to said diaphragm, a yoke on said rod lockinoliars supported by the lugs on said cover, and links from said yoke to said locking bars.

2. A tank closure comprising a collar-having a plurality of equally spaced downwardly projecting lu adjacent the bottom of the opening ther lirougg h, a cover adapted to be secured to said. collar having an equal number of downwardly projecting; lugs thereon correspondin in position with the lugs on said collar, a diaphragm in said cover. an operating rod attached to said diaphragm, a yoke on said rock locking liars supported by the lugs on said cover, links from said yoke to said locking: bars, and indici a on said collar and cover to show the relative positions of the lugs on said collar and cover.

8. A tank closure, comprisinga cover adapted to be attached to the tank, dia- FFHZD L. BUlllIllli-Ui. 

